The internet's increasing appetite for electricity poses a major threat to companies such as Google, according to scientists and industry executives.

Leading figures have told the Guardian that many internet companies are struggling to manage the costs of delivering billions of web pages, videos and files online – in a "perfect storm" that could even threaten the future of the internet itself.

"In an energy-constrained world, we cannot continue to grow the footprint of the internet … we need to rein in the energy consumption," said Subodh Bapat, vice-president at Sun Microsystems, one of the world's largest manufacturers of web servers.

Bapat said the network of web servers and data centres that store online information is becoming more expensive, while profits come under pressure as a result of the recession.

"We need more data centres, we need more servers. Each server burns more watts than the previous generation and each watt costs more," he said. "If you compound all of these trends, you have the perfect storm."

With more than 1.5 billion people online around the world, scientists estimate that the energy footprint of the net is growing by more than 10% each year. This leaves many internet companies caught in a bind: energy costs are escalating because of their increasing popularity, while at the same time their advertising revenues come under pressure from the recession.

One site under particular scrutiny is YouTube — now the world's third-biggest website, but one that requires a heavy subsidy from Google, its owner. Although the site's financial details are kept under wraps, a recent analysis by Credit Suisse suggested that it could lose as much as $470m (£317m) this year, as it succumbs to the high price of delivering power-intensive videos over the internet.

And while the demand for electricity is a primary concern, a secondary result of the explosion of internet use is that the computer industry's carbon debt is increasing drastically. From having a relatively small impact just a few years ago, it is now leapfrogging other sectors like the airline industry that are more widely known for their negative environmental impact.

However, tracking the growth of the internet's energy use is difficult, since internal company estimates of power consumption are rarely made public.

"A lot of this internet stuff is fairly secretive," Rich Brown, an energy analyst at the Lawrence Berkeley National Lab in California, told the Guardian.

"Google is probably the best example: they see it as a trade secret: how many data centres they have, how big they are, how many servers they have."

One study by Brown, commissioned by the US environmental protection agency, suggested that US data centres used 61bn kilowatt hours of energy in 2006. That is enough to supply the whole of the UK for two months, and 1.5% of the entire electricity usage of the US.

Brown said that despite efforts to achieve greater efficiency, internet use is growing at such a rate that it is outstripping technical improvements – meaning that American data centres could account for as much as 80bn kWh this year.

"Efficiency is being more than overwhelmed by continued growth and demand for new services," he said. "It's a common story … technical improvements are often taken back by increased demand."

Among the problems that could result from the internet's voracious hunger for electricity are website failures and communications disruption costing millions in lost business every hour – as well as power cuts and brownouts at plants which supply data centres with electricity.

To combat this, initiatives are taking place across the industry to cope with the problem, including new designs for data centres, innovative cooling methods and more investment in renewable energy.

Researchers at Microsoft's £50m research lab in Cambridge are even turning to older technology in an attempt to turn the clock back – by replacing energy-hungry new machines with the systems used in older, less powerful laptops.

"It turns out that those processors have been designed to be very energy efficient, basically to make batteries last," said Andrew Herbert, the director of Microsoft Research Cambridge.

"We found we can build more energy-efficient data centres with those than with the kind of high performance processors you find in a typical server."

Google was among the first internet companies to take action to reduce its footprint by developing its own data centres — but even though it pumped an estimated $2.3bn into infrastructure projects last year, it remains unclear whether it is winning the battle.

The company's vice-president of operations, Urs Hölzle, told the Guardian that it was struggling to contain energy costs. "You have exponential growth in demand from users, and many of these services are free so you don't have exponential growth of revenue to go with it," he said.

"With good engineering we're trying to make those two even out … but the power bill is going up."

Despite mounting evidence that the internet's energy footprint is in danger of running out of control, however, Hölzle dismissed concerns about the environmental impact of using the web as "overblown".

"One mile of driving completely dwarfs the cost of a search," he said. "Internet usage is part of our consumption, just like TV is, or driving. There is consumption there, but in the grand scheme of things I think it is not the problem."